Reactivity of Antibodies from Syphilis Patients to a Protein Array Representing the Treponema pallidum Proteome†

To identify antigens important in the human immune response to syphilis, the serum antibody reactivity of syphilitic patients was examined with 908 of the 1,039 proteins in the proteome of Treponema pallidum subsp. pallidum using a protein array enzyme-linked immunosorbent assay. Thirty-four proteins exhibited significant reactivity when assayed with human sera from patients in the early latent stage of syphilis. A subset of antigens identified were further scrutinized for antibody reactivity at primary, secondary, and latent disease stages, and the results demonstrate that the humoral immune response to individual T. pallidum proteins develops at different rates during the time course of infection. Over the past half century, effective antibiotic treatment programs have made syphilis relatively uncommon in the United States, with less than 7,100 primary and secondary cases diagnosed in 2003 (6). However, recent data indicate that reported cases are again increasing in subsets of the popula-tion, and periodic epidemics of syphilis have occurred for de-cades (5). In 1995, the number of new cases of syphilis world-wide was estimated to be 12 million per year (29)